The game is in full release. You wont see actual difficulty increases until you start getting to Super Hard, and then we get Extra Hard later on around Episode 4 - that's when enemies really start to become a challenge.

The game is very casual my friend. You won't get a challenge until Super Hard and/or once Episode 4 drops. So keep grinding those difficulties. If that a dealbreaker you may want to come back at a later date, but by then you may be behind the curve on gear.. soooo... weigh your options. The game has been around for 8 years, only in Beta in NA recently so you are pretty much already getting the idea what is in store for you. The challenge comes in Episode 4 and beyond tho, so there are quite a few things to look forward too. Might as well make sure you have all the mechanics down.